<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

</body>
<script type="text/javascript">
    let m = new Map();
    console.log(m);

    let m1 = new Map([
        ['k1', 'v1'],
        ['k2', 'v2'],
    ]);
    console.log(m1);
    console.log(m1.get('k1'));
    console.log(m1.set('k3', 'v3'));
    console.log(m1.has('k2'));
    m1.clear();
    console.log(m1);
</script>
</html>